Adaptive Compensation for Detuning in Pendulum Tuned Mass Dampers

Detuning, resulting from deterioration, inadvertent changes to structure properties, and design forecasting, can lead to a significant loss of performance in tuned mass dampers (TMDs). To overcome this issue, an adaptive compensation mechanism for suspended pendulum TMDs is proposed. The adaptive pendulum mass damper is a three-dimensional pendulum, augmented with a tuning frame to adjust its natural frequency, and two adjustable air dampers adjust damping. The adjustments for the natural frequency and damping compensation are achieved using a system of stepper motors and a microcontroller. There are two major components in the proposed methodology: identification and control, one followed by the other, in that order. The identification is carried out using spectral information obtained from the structural acceleration responses. The performance of the adaptive pendulum system is studied via both experiments and simulations. The main contribution of this paper is to develop an effective means of compensation for detuning in TMDs, while retaining the simplicity of passive pendulum TMDs. The proposed methodology allows pendulum TMDs to be tuned in place using relatively simple hardware and algorithms, based on ambient vibration measurements only.